This season diverges from the traditional formula used in previous seasons. Joan Watson has moved out of the brownstone and has started up her own private investigation agency. Sherlock joins MI-6 and relocates to London, England where he meets amateur investigator Kitty Winter. Getting fired from MI-6, Holmes returns to the United States with Kitty as his new apprentice. Bad blood between Joan and he continues to foment, but it isn't long before she finds herself aiding him on strange criminal cases once again.